Focussed ultrasound and nanomedicine offer new hope for improving effects of cancer drugs
Researchers have made a breakthrough in more precisely targeting drugs to cancers. Using ultrasound and lipid drug carriers (liposomes), a multi-disciplinary team of biomedical engineers, oncologists, radiologists and anaesthetists at the University of Oxford have developed a new way to improve the targeting of cancer drugs to tumours. The new technology has been used in humans for the very first time, with ultrasound remotely triggering and enhancing the delivery of a cancer drug to the tumour.
“Reaching therapeutic levels of cancer drugs within a tumour, while avoiding side effects for the rest of the body is a challenge for all cancer drugs, including small molecules, antibodies and viruses” says Professor Constantin Coussios, Director of the Oxford Centre for Drug Delivery Devices (OxCD3) and of the Institute of Biomedical Engineering at the University of Oxford. “Our study is the first to trial this new technique in humans, and finds that it is possible to safely trigger and target the delivery of chemotherapy deep within the body from outside the body using focussed ultrasound. Once inside the tumour, the drug is released from the carrier, supplying a higher dose of chemotherapy directly to the tumour, which may help to treat tumours more effectively for the same or a lower systemic dose of the drug.”
Published in The Lancet Oncology journal, the 10-patient phase 1 clinical trial used focussed ultrasound from outside the body to selectively heat liver tumours and trigger drug release from heat-sensitive carriers, known as thermosensitive liposomes. Building on over a decade of preclinical studies, the study demonstrated the ultrasound technique to be feasible, safe, and capable of increasing drug delivery to the tumour between two-fold and ten-fold in the majority of patients. Ongoing research worldwide is investigating the applicability of this technique to other tumour types, and future research could explore the combination of ultrasound with other drugs.
All 10 patients treated had inoperable primary or secondary tumours in the liver and had previously received chemotherapy. The procedure was carried out under general anaesthesia and patients received a single intravenous dose of 50 mg/m2 of doxorubicin encapsulated within low-temperature-sensitive liposomes (ThermoDox®, Celsion Corporation, USA). The target tumour was selectively heated to over 39.5o C using an approved ultrasound-guided focussed ultrasound device (JC200, Chongqing HAIFU, China) at the Early Phase Clinical Trials Unit at the Churchill Hospital in Oxford. In six out of 10 patients, the temperature at the target tumour was monitored using a temporarily implanted probe, whilst in the remaining four patients ultrasonic heating was carried out non-invasively.
Before ultrasound exposure, the amount of drug reaching the tumour passively was low and estimated to be below therapeutic levels. In seven out of 10 patients, chemotherapy concentrations within the liver tumour following focussed ultrasound were between two and ten times higher, with an average increase of 3.7 times across all patients.
“Only low levels of chemotherapy entered the tumour passively. The combined thermal and mechanical effects of ultrasound not only significantly enhanced the amount of doxorubicin that enters the tumour, but also greatly improved its distribution, enabling increased intercalation of the drug with the DNA of cancer cells” says Dr Paul Lyon, lead author of the study.
“This trial offers strong evidence of the rapidly evolving role of radiology in not only diagnosing disease but also in planning, guiding and monitoring therapy. The treatment was delivered under ultrasound guidance and patients were subsequently followed up by CT, MRI and PET-CT, evidencing local changes in tumours exposed to focussed ultrasound” commented Professor Fergus Gleeson, radiology lead co-investigator for the trial.
“A key finding of the trial is that the tumour response to the same drug was different in regions treated with ultrasound compared to those treated without, including in tumours that do not conventionally respond to doxorubicin” adds Professor Mark Middleton, principal investigator of the study. “The ability of ultrasound to increase the dose and distribution of drug within those regions raises the possibility of eliciting a response in several difficult-to-treat solid tumours. This opens the way not only to making more of current drugs but also targeting new agents where they need to be most effective. We can now begin to realize the promise of precision cancer medicine”.
NOTES TO EDITORS
This study was funded by the National Institute for Health Research Oxford Biomedical Research Centre, and further supported by the Oxford Centre for Drug Delivery Devices under a programme grant (EP/L024012/1) from the Engineering and Physical Sciences Research Council. It was conducted by researchers from the University of Oxford and Oxford University Hospitals NHS Foundation Trust. ThermoDox® was provided free of charge to the trial by Celsion Corporation, USA.
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Celsion’s most advanced program is a heat-mediated, tumor-targeting drug delivery technology that employs a novel heat-sensitive liposome engineered to address a range of difficult-to-treat cancers. The first application of this platform is ThermoDox®, a lyso-thermosensitive liposomal doxorubicin (LTLD), whose novel mechanism of action delivers high concentrations of doxorubicin to a region targeted with the application of localized heat at 40°C, just above body temperature. In one of its most advanced applications, ThermoDox®, when combined with radiofrequency thermal ablation (RFA), has the potential to address a range of cancers. For example, RFA in combination with ThermoDox® has been shown to expand the “treatment zone” with a margin of highly concentrated chemotherapy when treating individual primary liver cancer lesions. The goal of this application is to significantly improve efficacy.
Celsion’s LTLD technology leverages two mechanisms of tumor biology to deliver higher concentrations of drug directly to the tumor site. The first: Rapidly growing tumors have leaky vasculature, which is permeable to liposomes and enables their accumulation within tumors. Leaky vasculature influences a number of factors within the tumor, including the access of therapeutic agents to tumor cells. Administered intravenously, LTLD is engineered to allow significant accumulation of liposomes at the tumor site at the time of thermal ablation as these liposomes recirculate in the blood stream. The second: When the tumor tissue is heated to a temperature of 40°C or greater, the heat-sensitive liposome rapidly changes structure and the liposomal membrane selectively dissolves, creating openings that release the chemotherapeutic agent directly into the tumor and into the surrounding vasculature. Drug concentration increases as a function of the accumulation of liposomes at the tumor site, but only where the heat is present. This method targets only the tumor and the area related to tumor invasion, supporting precise drug targeting.
About Celsion Corporation
Celsion is a fully-integrated oncology company focussed on developing a portfolio of innovative cancer treatments, including directed chemotherapies, immunotherapies and RNA- or DNA-based therapies. The Company's lead program is ThermoDox®, a proprietary heat-activated liposomal encapsulation of doxorubicin, currently in Phase III development for the treatment of primary liver cancer and in Phase II development for the treatment of recurrent chest wall breast cancer. The pipeline also includes GEN-1, a DNA-based immunotherapy for the localized treatment of ovarian and brain cancers. Celsion has two platform technologies for the development of novel nucleic acid-based immunotherapies and other anti-cancer DNA or RNA therapies. For more information on Celsion, visit our website: http://www.celsion.com. (CLSN-LTSL/ThermoDox® CLSN-Optima Study/HCC)
Celsion wishes to inform readers that forward-looking statements in this release are made pursuant to the "safe harbor" provisions of the Private Securities Litigation Reform Act of 1995. Readers are cautioned that such forward-looking statements involve risks and uncertainties including, without limitation, unforeseen changes in the course of research and development activities and in clinical trials; the uncertainties of and difficulties in analyzing interim clinical data, particularly in small subgroups that are not statistically significant; FDA and regulatory uncertainties and risks; the significant expense, time, and risk of failure of conducting clinical trials; the need for Celsion to evaluate its future development plans; possible acquisitions or licenses of other technologies, assets or businesses; possible actions by customers, suppliers, competitors, regulatory authorities; and other risks detailed from time to time in the Celsion's periodic reports and prospectuses filed with the Securities and Exchange Commission. Celsion assumes no obligation to update or supplement forward-looking statements that become untrue because of subsequent events, new information or otherwise.